The present invention relates to a color filter layer of a liquid crystal display, and particularly to a color filter layer having black matrix comprising a light absorbing layer which doesn't scatter incident light rays.
Generally, the liquid crystal display for a pocket-sized or portable color television or computer has the form of a liquid crystal panel comprising color filters and thin film transistors, the construction of which is schematically illustrated in FIG. 1.
Namely, the liquid crystal display comprises a lower transparent glass substrate 10, an array of polycrystalline or amorphous silicon thin film transistors formed on the lower glass substrate, an upper transparent glass substrate 60, a color filter layer 50 of red, green and blue formed on the upper glass substrate, and a liquid crystal layer 30 sealingly filled between the two glass substrates.
Between the color filter layer 50 and the liquid crystal layer 30 a common electrode 40 of transparent indium tin oxide (ITO) is interposed. Each of the pixels of the liquid crystal panel contains a thin film transistor 20, which is controlled to turn on/off the pixel.
The present invention relates more specifically to the color filter layer 50.
The conventional color filter layer is illustrated in FIG. 2.
Referring to FIG. 2, each of the pixels of the color filter layer 50 formed on the upper transparent glass substrate 60 comprises dyes of red, green and blue patterned in a mosaic (linearly patterned in the drawing). The color filters of red, green and blue 52R, 52G, 52B may be formed by the conventional printing method or the photo-sensitive filming method. A black matrix comprising chromium(Cr) is interposed between the color filters. The black matrix 51 is to block the light rays incident between the pixels through the glass substrate 60, which can prevent displaying undesired colors due to overlapping of the adjacent color filters 52R, 52G, 52B. Although the black matrix is illustrated to be formed of chromium in FIG. 2, to commonly known dyestuff may be used instead of chromium.
When the light rays incident through the glass substrate 60 pass the color filters 52R, 52G, 52B of red, green and blue corresponding to the operated pixels, the colors are displayed. However, the light rays are blocked in the black matrix. Such conventional color filter layers incorporating a black matrix are capable of blocking some incident light rays, but cannot prevent scattering of the light rays. If all incident light rays were to be completely blocked by the black matrix, the color display of the pixels would have a high contrast, thereby improving the resolution. However, the conventional black matrix comprising chromium or a dyestuff can not prevent the scattering of the light rays because of its inherent characteristics. Thus, the scattering of the light rays from the black matrix affects the color filters so as to reduce the contrast.